There are several models of Optiplex 755s. There is the desktop model (which sits horizontally on a desk and requires Low-Profile) and there is the mini-tower (what normal people would consider a tower). Please keep in mind that the mini-tower version is a reversed motherboard. What I mean to say is that the right panel of the tower comes off, not the left panel. Almost like a BTX case (Dell might have even used the BTX form factor, with their own special twist). I purchased an nVidia GT430 fanless card from NewEgg to go in the mini-tower (<a href="http://www.newegg.com/Product/Product.aspx?Item=N82E16814500175&cm_re=GT430-_-14-500-175-_-Product">http://www.newegg.com/Product/Product.aspx?Item=N82E16814500175&cm_re=GT430-_-14-500-175-_-Product</a>). That is a two bracket wide card. The BTX nature of that case means the nvidia card is put in "upside down". This means the vent bracket needs to be put in a slot ABOVE the PCIe slot on the mobo. The Dell Optiplex 755 doesn't have a slot above the PCIe on the motherboard. However, since the design of that particular case puts a fan/vent directly where the second "vent" bracket of the nVidia card would be, I simply dremelled off the vent bracket and the card installed no problem. I've been running it for months in this config and I have had 0 problems. The whole rig is pretty darned silent as well. I'm thrilled. If you have any questions about this install, just let me know. Now I just need a new receiver capable of HDMI in, and I'll be the happiest Myth-er there is!<br>
<br>Jim<br>